In general, a wireless communication apparatus refers to a unit that transmits and receives data over a wireless communication channel. This wireless communication apparatus is installed inside or outside of a data processing device, such as a notebook computer, desktop computer or personal digital assistant (PDA), to enable the data exchange of the data processing device with other data processing devices. FIG. 1 schematically shows the configuration of a general wireless communication system. Although wireless communication apparatuses 11 and 12 can generally perform both transmission and reception of data, hereinafter, for the convenience of description, on the basis of one data frame, the wireless communication apparatus 11 that transmits the data frame will be referred to as a transmitting node and the wireless communication apparatus 12 that receives the data frame will be referred to as a receiving node. The receiving node 12 sends an acknowledge frame to the transmitting node 11 after receiving the data frame. Therefore, in this wireless communication system, the transmitting node 11 can check the transmission state of the data frame transmitted thereby through the acknowledge frame.
A representative example of such a wireless communication apparatus is an IEEEE 802.11 wireless local area network (LAN) card that is used in wireless LAN construction. However, in this wireless communication apparatus, wireless signals being transmitted and received between the transmitting node 11 and the receiving node 12 may be subject to interference from wireless signals of different bands adjacent to a wireless communication channel between the transmitting node 11 and the receiving node 12. In addition, in the case where a wider gap or obstacles are present between the transmitting node 11 and the receiving node 12, the signals being transmitted and received may be attenuated, resulting in a degradation in quality of the channel, for example, an irregular variation in the channel quality, and in turn a degradation in data transmission capability of the channel.
In this regard, it is very important in the wireless communication apparatus to estimate the quality of the wireless communication channel and properly adjust the transfer rate of the channel according to the estimation result to balance the transmission quality of the channel.
To this end, a conventional wireless communication apparatus is adapted to estimate the transmission quality of a wireless communication channel on the basis of only the number of data frames failed to be transmitted, among the past transmission conditions of the channel, or on the basis of only a received signal strength (RSS) in data transmission. For example, in the case where the number of data frames failed to be transmitted exceeds a reference value, or the RSS falls below a reference value, the wireless communication apparatus determines that interference has occurred in the wireless communication channel, and thus adjusts the transfer rate of the channel.
However, in the aforementioned conventional quality estimation, it is difficult to definitely state that the transmission quality will also be good in the future even though the past transmission was successful. For this reason, when the transmission quality is estimated on the basis of only the number of data frames failed to be transmitted in the past as stated above, reliability of the estimation result is reduced. Moreover, when interference has occurred, the transmission quality is degraded, but the RSS may often be high. As a result, where the transmission quality is estimated on the basis of only the RSS, external interference makes it difficult to collect accurate RSS values.